title: Enhancing the [13C]bicarbonate signal in cardiac hyperpolarized [1-13C]pyruvate MRS studies by infusion of glucose, insulin and potassium.
abstract: A change in myocardial metabolism is a known effect of several diseases. MRS with hyperpolarized (13)C-labelled pyruvate is a technique capable of detecting changes in myocardial pyruvate metabolism, and has proven to be useful for the evaluation of myocardial ischaemia in vivo. However, during fasting, the myocardial glucose oxidation is low and the fatty acid oxidation (β-oxidation) is high, which complicates the interpretation of pyruvate metabolism with the technique. The aim of this study was to investigate whether the infusion of glucose, insulin and potassium (GIK) could increase the myocardial glucose oxidation in the citric acid cycle, reflected as an increase in the [(13)C]bicarbonate signal in cardiac hyperpolarized [1-(13)C]pyruvate MRS measurements in fasted rats. Two groups of rats were infused with two different doses of GIK and investigated by MRS after injection of hyperpolarized [1-(13)C]pyruvate. No [(13)C]bicarbonate signal could be detected in the fasted state. However, a significant increase in the [(13)C]bicarbonate signal was observed by the infusion of a high dose of GIK. This study demonstrates that a high [(13)C]bicarbonate signal can be achieved by GIK infusion in fasted rats. The increased [(13)C]bicarbonate signal indicates an increased flux of pyruvate through the pyruvate dehydrogenase enzyme complex and an increase in myocardial glucose oxidation through the citric acid cycle.
authors.affiliation: Danish Research Centre for Magnetic Resonance (DRCMR), Copenhagen University Hospital Hvidovre, Hvidovre, Denmark.
authors.forename: Mette Hauge
authors.initials: MH
authors.lastname: Lauritzen
authors.forename: Christoffer
authors.initials: C
authors.lastname: Laustsen
authors.forename: Sadia Asghar
authors.initials: SA
authors.lastname: Butt
authors.forename: Peter
authors.initials: P
authors.lastname: Magnusson
authors.forename: Lise Vejby
authors.initials: LV
authors.lastname: Søgaard
authors.forename: Jan Henrik
authors.initials: JH
authors.lastname: Ardenkjær-Larsen
authors.forename: Per
authors.initials: P
authors.lastname: Åkeson
mesh_terms: D000409:Alanine / Q000378:metabolism; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism*; D001786:Blood Glucose / Q000378:metabolism; D002247:Carbon Isotopes; D005947:Glucose / Q000008:administration & dosage / Q000494:pharmacology*; D007328:Insulin / Q000008:administration & dosage / Q000494:pharmacology*; D007773:Lactates / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D011188:Potassium / Q000008:administration & dosage / Q000494:pharmacology*; D019289:Pyruvic Acid / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012815:Signal Processing, Computer-Assisted
chemical_list: D001639:Bicarbonates; D001786:Blood Glucose; D002247:Carbon Isotopes; D007328:Insulin; D007773:Lactates; D019289:Pyruvic Acid; D005947:Glucose; D000409:Alanine; D011188:Potassium
keywords: 13C; MRS; cardiac metabolism; glucose; hyperpolarization; insulin; pyruvate dehydrogenase